Preterm birth is a multifactorial disease involving activation of uterine contractions and/or decreased cervical competence, which can be the result of an inflammatory, infectious or ischemic insult to the uteroplacental barrier (see Mauldin J G and Newman R B. “Preterm birth risk assessment.” in Semin Perinatol 2001;4:215-22). Preterm labor, defined as uterine contractions or preterm premature rupture of the fetal membranes before 37 weeks gestational age, accounts for some 80% of all preterm deliveries (see Goldenberg R, Hauth J C, and Andrews W W. “Intrauterine infection and preterm delivery.” in New Engl J Med 2000:342:1500-7). There is little doubt that cytokine secretion by inflammatory cells plays an important role in the initiation of infection-induced parturition (see Dudley D J. “Immunoendocrinology of preterm labor: the link between corticotropin-releasing hormone and inflammation.” in Am J Obstet Gynecol 1999; 180: S251-6). It seems likely that IL-6 (see Opsjon et al. “Tumor necrosis factor, interleukin-1 and interleukin-6 in normal human pregnancy.” in Am J Obstet Gynecol 1993;169:397-404) and IL-8 (see Arici et al. “Interleukin-8 induces proliferation of endometrial stromal cells: a potential autocrine growth factor.” in J Clin Endocrinol Metab 1998;83:1201-5) are also involved in the normal localized growth required for successful pregnancy. However, their involvement in normal parturition appears to be facilitative rather than initiative. Thus, in the absence of chorioamnionitis, as the cervix dilates, there is increased contact between the decidua/fetal membranes and the upper genital tract. This contact results in the locally increased production of several inflammatory cytokines, albeit at lower concentrations than in infection-induced parturition, and this augments and drives both uterine contraction and further cervical dilatation via the induction of prostaglandins (see Mitchell M D, Dudley D J, Edwin S S and Lundin-Schiller S. “Interleukin-6 stimulates prostaglandin production by human amnion and decidual cells.” in Eur J Pharm 1991;192:189-91) and matrix metalloproteinases (see Winkler M, Oberpichler A, Tschetsche H, Ruck P, Fischer D C and Rath W. “Collagenolysis in the lower uterine segment during parturition at term: correlations with stage of cervical dilatation and duration of labor.” in Am J Obstet Gynecol 1999:181:153-8). In this manner, both an inflammatory response and decidual activation are initiated and/or augmented, accelerating the subsequent events leading to birth.
Pre-B-cell colony enhancing factor (PBEF) was first identified from activated peripheral blood lymphocytes and shown to be involved in the maturation of B-cell precursors (see Samal B, Sun Y, Stearns G, Xie C, Suggs S and McNiece I. “Cloning and characterization of the cDNA encoding a novel human pre-B-cell colony-enhancing factor.” in Mol Cell Biol 1994; 14:1431-7). In studying the effects of acute distension on the genes expressed by human amniotic epithelial cells (WISH), one of these genes was identified as PBEF (see Nemeth E, Tashima L S, Yu Z and Bryant-Greenwood G D. “Fetal membrane distension I. Differentially expressed genes regulated by acute distension in amniotic epithelial (WISH) cells.” in Am J Obstet Gynecol 2000;192:50-9; referred to hereinafter as “Nemeth I”). When preterm and term full-thickness fetal membranes were similarly distended in vitro, it was shown that the expression of the PBEF gene was greater in the preterm than in the term membranes (see Nemeth E, Millar L K and Bryant-Greenwood G. “Fetal membrane distension: II. Differentially expressed genes regulated by acute distension in vitro.” in Am J Obstet Gynecol 2000; 182:60-7; referred to hereinafter as “Nemeth II”). This suggested that by term, the tissue had attained its maximum distension, and sensitivity to further distension was then limited. While distension is a part of the normal process of pregnancy, uterine contractions also cause distension, thus distension is also a key part of the labor process.
A genomic clone of PBEF was subsequently analysed and shown to be a highly regulated gene. An important finding in this study was the identification of an NF-κB binding element in the third intron, likely to be responsible for the responsiveness to distension (see Ognjanovic S, Bao S, Yamamoto S Y, Garibay-Tupas J, Samal B, and Bryant-Greenwood G D. “Genomic organization of the gene coding for human pre-B cell colony-enhancing factor and expression in human fetal membranes.” in J Mol Endocrinol 2001;26:107-117). PBEF was also localized with a specific antiserum, showing that the expression of the PBEF gene was significantly upregulated in severely infected membranes. In addition, the neutrophils present in these tissues stained darkly for PBEF, suggesting that they are an additional source of PBEF in the setting of infection (see Ognjanovic et al., supra). However, while LPS, TNF-α, IL-1β and IL-6 all induced PBEF gene expression, it has been shown that IL-8 treatment had no such effect (see Ognjanovic et al., supra). This was particularly interesting because IL-8 and PBEF expression both increased when WISH cells and the fetal membranes were acutely distended (see Nemeth I and Nemeth II, supra). Therefore, like PBEF, IL-8 appears to be responsive to distension in a sterile situation, as well as being induced by infection, but its relationship with PBEF under these conditions is unknown.
PBEF is present in fetal membranes during normal gestation and parturition in the absence of infection. Its expression increases with both preterm labor and normal labor at term. Moreover, PBEF causes an increase in the expression in fetal membranes of many key proteins that are known activators of the labor process (see, for example, FIG. 5). Thus, it was investigated whether PBEF could serve as a useful marker for identifying patients in true labor, providing new diagnostic modalities not previously available. Furthermore, it was investigated whether the action of PBEF could be blocked, or its expression blocked, thereby stopping the labor process and providing new treatment modalities not previously available.